RESUMO
OBJECTIVES: To explore the differences in erythrocyte hydrogen sulfide (H2S) production in children with vasovagal syncope (VVS). STUDY DESIGN: A total of 54 children including 27 with VVS, aged 6-16 years (mean age 11.3 ± 3.3 years), and 27 healthy children, aged 3-17 years (mean age 10.4 ± 1.8 years) were included in the study. Children with VVS had symptoms of dizziness, pallor, blurred vision, nausea, and some had syncope. Erythrocyte H2S production was measured by a sulphur-sensitive electrode. Flow-mediated dilation (FMD) of brachial artery was measured for each patient by vascular ultrasound. RESULTS: H2S production from erythrocytes was significantly increased in the children with VVS compared with controls (P < .01). The erythrocytic H2S production in the VVS-vasoinhibitory subgroup was obviously higher than that in VVS-cardioinhibitory (P < .05) and VVS-mixed inhibitory subgroups (P < .05). FMD in the VVS-vasoinhibitory subgroup was greater than that in the VVS-cardioinhibitory (P < .05) and the VVS-mixed subgroups (P < .05). The erythrocytic H2S production had a positive linear correlation with FMD in children with VVS (P < .05). CONCLUSIONS: Increased erythrocyte H2S production may be involved in the pathogenesis of VVS in children.
Assuntos
Eletrocardiografia , Eritrócitos/metabolismo , Frequência Cardíaca/fisiologia , Sulfeto de Hidrogênio/sangue , Síncope Vasovagal/sangue , Adolescente , Biomarcadores/sangue , Criança , Pré-Escolar , Progressão da Doença , Feminino , Seguimentos , Humanos , Masculino , Curva ROC , Síncope Vasovagal/diagnóstico , Síncope Vasovagal/fisiopatologia , Teste da Mesa InclinadaRESUMO
OBJECTIVE: To investigate whether 24-hour urinary sodium excretion could be an indicator of the effectiveness of salt supplementation in children with postural orthostatic tachycardia syndrome (POTS). STUDY DESIGN: The patient group comprised 30 children with POTS, and the control group comprised 10 healthy children. Serum sodium and 24-hour urinary sodium excretion were measured in all children, and the relationship between 24-hour urinary sodium and symptom severity was analyzed in the 30 patients. At 1 month after initiation of salt supplementation, the receiver operating characteristic curve was used to explore the probability of correctly discriminating responders to salt supplementation from nonresponders using 24-hour urinary sodium excretion as an indicator. RESULTS: Patients with POTS had lower 24-hour urinary sodium excretion than controls (P = .022). Symptom severity was negatively correlated with 24-hour urinary sodium excretion (OR, -0.754; P = .000). The receiver operating characteristic curve demonstrated a sensitivity of 76.9% and specificity of 93% for correct prediction of responders and nonresponders to salt supplementation when a 24-hour urinary sodium excretion of 124 mmol/24 hours was used as the cutoff value. CONCLUSION: Our results indicate that 24-hour sodium excretion of <124 mmol/24 hours is an indicator of the effectiveness of salt supplementation in children and adolescents with POTS.